ONTOGENY OF THE INTRARENAL KALLIKREIN-KININ SYSTEM - PROPOSED ROLE INRENAL DEVELOPMENT

The kallikrein-kinin system (KKS) plays an important role in the regul ation of renal function. Endogenous kinins modulate renal microvascula r resistance, medullary blood flow, and distal nephron sodium and wate r reabsorption. All the components of the KKS, including tissue kallik rein, kininogen, kininase II, and kinin receptors are expressed within the kidney, establishing a paracrine system capable of controlling lo cal nephron functions. In this review, data will be presented demonstr ating that the developing kidney expresses an endogenous, functionally active KKS. Molecular studies have shown that gene expression of the renal KKS in the rat is activated postnatally, and that the intrarenal distribution of KKS components is subject to developmental control. F urthermore, the developmental expression of KKS appears to be regulate d primarily at the transcriptional level. Ontogenetic studies have als o revealed that the bradykinin B-2 receptor gene is overexpressed in t he developing rat kidney. As kinins are potent vasoactive and growth-p romoting factors, it is proposed that endogenous kinins mediate develo pmental renal growth and differentiation, and modulate the maturationa l changes which occur in renal hemodynamics. (C) 1997 Wiley-Liss, Inc.